BIOLOGY FOR ENGINEERS (21BE45)

Module 4

NATURE-BIOINSPIRED MATERIALS AND MECHANISMS

Syllabus:
Echolocation (ultrasonography, sonars), Photosynthesis (photovoltaic cells, bionic leaf). Bird flying (GPS and
aircrafts), Lotus leaf effect (Super hydrophobic and self-cleaning surfaces), Plant burrs (Velcro), Shark skin
(Friction reducing swim suits), Kingfisher beak (Bullet train). Human Blood substitutes - hemoglobin-based
oxygen carriers (HBOCs) and perflourocarbons (PFCs).

ECHOLOCATION

In nature’s sonar system, echolocation occurs when an animal emits a sound wave that bounces off an
object, returning an echo that provides information about the object’s distance and size. Over a thousand species
echolocate, including most bats, all-toothed whales, and small mammals.

The basic principle of echolocation involves emitting sound waves, usually in the form of clicks or
chirps, and then listening to the echoes that bounce back after these sounds hit objects in the environment. By
analyzing the returning echoes, the animals can form a mental map of their surroundings, detect obstacles,
locate prey, and even identify the size and shape of objects.

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BIOLOGY FOR ENGINEERS (21BE45)

ULTRASONOGRAPHY

Ultrasound:
Ultrasound refers to sound above the human audible limit of 20 kHz. Ultrasound of frequencies up to 10
MHz and beyond is used in medical diagnosis, therapy, and surgery.
Mechanism
The Ultrasound transducer is then moved over the skin in the region of interest. The transducer emits
sound waves that penetrate through the skin and tissues and then bounce back when they encounter different
structures, such as organs or blood vessels. These returning sound waves are called echoes.
The echoes are picked up by the transducer and sent to a computer that processes the information and
creates real-time images on a monitor. The images are based on the patterns and strength of the returning sound
waves, allowing visualization of the internal structures.

SONAR:

Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound
propagation (usually underwater, as in submarine navigation) to navigate, measure distances (ranging),
communicate with or detect objects on or under the surface of the water, such as other vessels.

Sonar can be classified into two types:

• passive sonar means detection of pulses of sound waves made by vessels (Ships)
• active sonar means the emitting pulses of sounds and detection for echoes.

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BIOLOGY FOR ENGINEERS (21BE45)

Sonar is as a means of acoustic location and measurement of the echo characteristics of "targets" in the
water. The term sonar is also used for the equipment used to generate and receive the sound. The acoustic
frequencies used in sonar systems vary from very low (infrasonic) to extremely high (ultrasonic). The study of
underwater sound is known as underwater acoustics or hydroacoustics. Sonar is also used for robot navigation,
and SODAR (an upward-looking in-air sonar) in atmospheric investigations.

PHOTOSYNTHESIS:

Most life on Earth depends on photosynthesis. This process is carried out by plants, algae, and some
types of bacteria, which capture energy from sunlight to produce oxygen (O 2) and chemical energy stored in
glucose (a sugar). During photosynthesis, plants take in carbon dioxide (CO2) and water (H2O) from the air and
soil. Within the plant cell, the water is oxidized (which loses electrons), while the carbon dioxide is reduced (it
gains electrons). This transforms the water into oxygen and the carbon dioxide into glucose. The plant then
releases the oxygen back into the air, and stores energy within the glucose molecules.

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BIOLOGY FOR ENGINEERS (21BE45)

PHOTOVOLTAIC CELLS

A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into
electricity by the photovoltaic effect, which is a physical and chemical phenomenon. It is a form of
photoelectric cell, defined as a device whose electrical characteristics, such as current, voltage, or resistance,
vary when exposed to light. Individual solar cell devices are often the electrical building blocks of photovoltaic
modules, known colloquially as solar panels. The common single-junction silicon solar cell can produce a
maximum open-circuit voltage of approximately 0.5 volts to 0.6 volts.

Application of photovoltaic cells:

• Remote Locations
• Stand-Alone Power
• Power in Space
• Building-Related Needs
• Military Uses
• Transportation

BIONIC LEAF
Bionic leaf uses sunlight and converts carbon dioxide (CO2) from the atmosphere into usable fuels or
other valuable chemical compounds using renewable energy sources. Bionic leaves can be composed of both
synthetic (metals, ceramics, polymers, etc.) and organic materials (bacteria), or solely made of synthetic
materials. The Bionic Leaf has the potential to be implemented in communities, such as urbanized areas to
provide clean air as well as providing needed clean energy.
Mechanism
Solar Panels: The system starts with solar panels or photovoltaic cells that capture sunlight and convert it into
electricity. This serves as the energy source for the entire process.

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BIOLOGY FOR ENGINEERS (21BE45)

Electrolyzer: The electricity generated from the solar panels powers an electrolyzer. The electrolyzer splits
water (H2O) into oxygen (O2) and hydrogen (H2) through a process called electrolysis.
Hydrogen Gas: The produced hydrogen gas is collected and used in the next step.
Catalyst: The bionic leaf employs a specialized catalyst to facilitate the conversion of carbon dioxide (CO2)
and hydrogen (H2) into a liquid fuel or other useful chemicals.
Product Collector: The liquid fuel or chemical products are collected and stored for future use.
Oxygen Release: During the process, oxygen is also released as a byproduct, just like in natural photosynthesis.
This oxygen can be released into the environment.

BIRD FLYING:

Bird flight is one of the most complex forms of locomotion in the animal kingdom. Each facet of this type of
motion, including hovering, taking off, and landing, involves many complex movements. Flight assists birds
with feeding, breeding, avoiding predators, and migrating.

GPS (Global Positioning System)

GPS stands for Global Positioning System. It is a satellite-based navigation system that allows users to
determine their precise location and time anywhere on or near the Earth. The GPS system works by utilizing a
network of at least 24 satellites orbiting the Earth, which continuously transmit signals containing time and
position information. It’s made up of three parts: satellites, ground stations, and receivers.

Satellites: These are the networking machines orbiting round the earth which are supposed to be at any given
time.
Ground stations: The ground stations uses radar to send and detect the signal between the satellites.
Receiver: These are mobile phone or any electronic gadgets which constantly receives the signal from the
orbiting satellites. Using the trilateration process, the receiver locates its position as the signals are obtained
from at least three satellites. The receiver figures out how far distance or location etc

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BIOLOGY FOR ENGINEERS (21BE45)

AIRCRAFT

Lift, Drag, and Thrust:

• The fundamentals of bird flight are similar to those of aircraft, in which the aerodynamic forces sustain
flight lift, drag, and thrust.

• Lift force is produced by the action of airflow on the wing, which is an airfoil.

• The airfoil is shaped such that the air provides a net upward force on the wing, while the movement of
air is directed downward.

• The additional net lift may come from airflow around the bird's body in some species, especially during
intermittent flight while the wings are folded or semi-folded.

• Aerodynamic drag is the force opposite to the direction of motion, and hence the source of energy loss
in flight. The drag force can be separated into two portions,

• Lift-induced drag, which is the inherent cost of the wing producing lift (this energy ends up primarily in
the wingtip vortices).

• Parasitic drag, including skin friction drag from the friction of air and body surfaces and form drag from
the bird's frontal area.

LOTUS LEAF EFFECT

The lotus leaf is well-known for having a highly water-repellent, or superhydrophobic, surface, thus giving the
name to the lotus effect. Water repellency has received much attention in the development of self-cleaning
materials, and it has been studied in both natural and artificial systems.

Mechanism:

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BIOLOGY FOR ENGINEERS (21BE45)

An autonomous mechanism to achieve self-cleaning on super hydrophobic surfaces, where the contaminants are
removed by self-propelled jumping condensate powered by surface energy. Super hydrophobic surfaces
typically have a micro- and nano-scale rough texture that traps air pockets, reducing the solid-liquid contact
area. This texture helps create the water-repellent effect. Designing and optimizing this texture is crucial to
ensure water droplets can easily roll off, taking dirt and debris with them.

PLANT BURRS AND VELCRO

A bur (also spelled burr) is a seed or dry fruit or infructescence that has hooks or teeth. The main
function of the bur is to spread the seeds of the bur plant, often through epizoochory. The hooks of the bur are
used to catch on to for example fur or fabric, so that the bur, which contains seeds, then can be transported
along with the thing it attached itself to. Another use for the spines and hooks is physical protection against
herbivores. Their ability to stick to animals and fabrics has shaped their reputation as bothersome

The bur of burdock was the inspiration for the hook and loop fastener, also known as Velcro.

Experimentation/ Mechanism: Velcro's name is a combination of "vel" from velvet (representing the loops)
and "cro" from crochet (representing the hooks). The invention of Velcro revolutionized the fastening industry,
and it is now used in a wide range of applications, from clothing and shoes to aerospace and medical equipment.
It’s simple yet effective design has made it a highly successful and iconic fastening solution worldwide.

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BIOLOGY FOR ENGINEERS (21BE45)

SHARK SKIN

Sharks have small denticles, tooth-like structures found on their skin. These denticles are designed to
reduce drag and turbulence in the water, allowing sharks to move through the water more efficiently. These
denticles inspired the development of specialized swimwear known as "sharkskin" or "sharkskin-inspired"
swimsuits. The developed shark skin materials are wrinkle-resistant, highly breathable and they doesn't trap
sweat and makes the person to feel fresh all day.

KINGFISHER BEAK

The kingfisher's beak has a pointed shape and smooth surface, which helps it reduce drag and efficiently
move through both air and water. The fine point of the conical beak presents little surface area or resistance to
the water upon entry, and the evenly and gradually enlarging cross-section of the beak keeps fluid flowing
smoothly around it as it penetrates further into the water column. This makes the bird to reach the fish before
the fish knows to flee. The streamlined design of the kingfisher's beak, which allows it to enter the water with
minimal splashing and disruption which gives more insights into aerodynamics and fluid dynamics.

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BIOLOGY FOR ENGINEERS (21BE45)

Bullet train

• Eiji Nakatsu, the chief engineer of the company operating Japan’s fastest trains, wondered if the
kingfisher’s beak might serve as a model for how to redesign trains not to create such a thunderous noise
when leaving tunnels and breaking through the barrier of tunnel air and outside-air.

• The optimum shape for the front of the new train became quieter and more efficient as the geometry of
its nose became more like the shape of a kingfisher’s beak, requiring 15% less energy while traveling
even faster than before.

HUMAN BLOOD SUBSTITUTES

Human blood substitutes, also known as artificial blood or blood substitutes are substances designed
to mimic some functions of natural blood and serve as temporary replacements for human blood in certain
medical situations. These substitutes aim to address blood transfusion challenges, such as blood shortages,
compatibility issues, and the need for immediate availability in emergencies.

Some of the main types of human blood substitutes include:

Hemoglobin-based Oxygen Carriers (HBOCs): HBOCs are solutions that contain purified and modified
hemoglobin, the protein responsible for carrying oxygen in red blood cells. These solutions can transport and
deliver oxygen to tissues and organs. HBOCs have been tested for use in situations where red blood cell
transfusions are not feasible or available.

Perfluorocarbons (PFCs): PFCs are synthetic compounds that can dissolve and transport large amounts of
oxygen and carbon dioxide. They have been studied for their potential use in oxygen delivery in situations
where conventional blood is not available or suitable.

Synthetic Oxygen Carriers: These are artificial molecules designed to carry and release oxygen to tissues
similarly to natural hemoglobin. They are still in the experimental stages of development.

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